The invention relates to a device for regulating the flow cross section in the cooling air inflows of a bulk material grate cooler for cooling hot bulk material such as cement clinker, for example, with a regulator housing which is integrated into the cooling air inflow below the cooling grate and in which a control element is moved in such a way that an increase in the flow rate in the region of the control element and, associated therewith, an incipient increase in the cooling air flow quantity bring about a reduction in the free flow cross section, and vice versa.
In a cement clinker production line, the hot cement clinker produced from calcined cement raw meal in a rotary tubular kiln is discharged from the kiln delivery end onto a cooler, as a rule onto the cooling grate of a grate cooler, is distributed thereon and is moved in the longitudinal direction toward the cooler delivery end by suitable conveying means, the cooling grate and the hot bulk material layer being passed through essentially from the bottom to the top by cooling air flows. The known grate cooler types are explained briefly below.
In a push grate cooler, stationary grate plate rows alternate with reciprocating grate plate rows seen in the conveying direction, all the grate plates are provided with cooling air openings and they are flowed through essentially from the bottom to the top by cooling air, and the combined oscillating movement of all the movable grate plate rows gradually transports the hot material to be cooled and in so doing cools it. As an alternative to such a push grate cooler, a grate cooler type in which the cooling grate flowed through by cooling air is not moved but is stationary is known from EP-B-1 021 692, for example. A number of rows of adjacent reciprocating beam-shaped pushing elements are arranged above the stationary grate surface and are moved between a forward stroke position in the direction of transport of the material being cooled and a return stroke position, so that the material is likewise moved successively, and in the process cooled, from the cooler start to the cooler end by the reciprocating movement of these pushing elements in the material bed to be cooled.
In such grate coolers, it is not always possible to avoid uneven distributions in the hot bulk material bed with regard to bulk material bed height, clinker grain size, temperature profile etc., which results in non-uniform cooling. This is because, in cooling grate regions with a greater bulk material bed height, the flow resistance for the cooling air increases, the flow rate falls and less cooling air is conducted through the bulk material bed, and conversely, in cooling grate regions with a small bulk material bed height, the flow resistance for the cooling air falls, its flow rate and the risk of an air breakthrough increase, and too great a cooling air quantity is conducted through precisely those bulk material bed regions which would require the smallest cooling air quantity.
It is therefore known in a grate cooler for cooling hot bulk material such as cement clinker (EP-B-0 848 646) to regulate the respective cooling air quantity in the cooling air inflows below the cooling grate automatically in each case in such a way that, when the cooling air flow quantity starts to increase, as a result of the bed height of material being cooled becoming smaller and the flow resistance decreasing, the clear cross-sectional area of the cooling air inflow lines concerned is reduced, and vice versa, so as in this way to compensate for a changing pressure drop over the bed of material being cooled, so that the cooling air quantity concerned is no longer dependent on the respective pressure loss or flow resistance of the cooling air in the zone concerned of the bed of material being cooled. In this connection, the known mechanical cooling air flow regulator operates with a weight-loaded swing flap with a horizontal pivoting axis, the swing flap automatically throttling the respective cooling air inflow to a greater or lesser extent according to the prevailing pressure conditions and flow conditions. If the known cooling air regulating device, which operates automatically with a pivoting lever weight actuated purely by gravity with a body acted on by the flow, were arranged below the cooling grate in the cooling air inflows of cooling grate zones which are not stationary but which, as in a push grate cooler, are reciprocated together with regulating devices for the purpose of bulk material transport, the automatic regulation of the regulating device would be disrupted by the reciprocating vibrating movement and the regulation result would thus be distorted.
A cooling air regulating device in a bulk material grate cooler is also known from WO 02/06748. In this device, a round stationary segment disk provided with through-openings is arranged in the cooling air supply line below the grate, and a vane disk mounted rotatably on a spindle is arranged above the segment disk, the vane disk rotating depending on the flow rate of the cooling air and in the process automatically varying the clear flow cross section of the segment disk in such a way that the vane disk is rotated counter to a spring force and the flow cross section is reduced when the flow rate increases, and vice versa. The risk that the functioning of the regulating device will be disrupted by the intermittent oscillating movement of the reciprocating cooling grate zones is not excluded in this automatically operating cooling air regulating device either.